Refrigeration systems



2 May 24, 1966 Filed Dec. 2, 1964 T. D. H. ANDREWS REFRIGERATION SYSTEMS2 Sheets-Sheet 1 INVENTOE THOMAS M. ANDREWS MW! m ATTORNEY May 24, 1966T. D. H. ANDREWS 3,252,298

Filed Dec. 2, 1964 REFRIGERATION SYSTEMS 2 Sheets-Sheet 2 INVENTORTHOMAS D. H. ANDREWS EA/Mm mm A-rw-oszwav United States Patent 3,252,298REFRIGERATION SYSTEMS Thomas D. H. Andrews, Cheltenham, England,assignor to Dowty Technical Developments Limited, Cheltenharn, England,a British company Filed Dec. 2, 1964, Ser. No. 415,294 Claims priority,application Great Britain, Dec. 7, 1963, 48,409/63 6 Claims. (Cl.62-323) This invention relates to refrigeration systems.

According to the invention there is provided a closedcircuitcompressor-type refrigeration system in which the compressor is drivenby a turbine, in turn powered by the exhaust discharging from anassociated engine. When the refrigeration system is used in anengine-driven vehicle, the exhaust discharge which powers the turbinewill be derived from the engine driving the vehicle.

The refrigeration system, which also includes a condenser, receiver andevaporator, in conventional manner, may be so arranged that a relativelylarge flow of refrigerant is circulated at relatively low pressure sothat only ice From the delivery port 29 of the compressor 15 a pipe 30is taken to connect with the pipe 27 at the inlet of the condenser 17,the pipe 30 including an outlet service valve 31 positioned justdownstream of the port 29.

The condenser is so positioned with respect to the vehicle that coolingair can be passed across it, and the outiet side of the condenser isconnected by a pipe 32 to the liquid receiver 16 which, in conventionalmanner, also a relatively low compression ratio across the compressor isrequired for the refrigeration function. In this way a turbine ofrelatively smallsize can be employed.

The compressor may be of centrifugal type and the refrigerant of suchnature that the tip speed of the compressor rotor is maintained belowsonic velocity in that refrigerant, and thus a critical gas speed inoperation of the compressor is avoided.

Sealing means may be provided between the compressor and turbine, aportion of the sealing means being effective when the turbine andcompressor are operating, and another portion thereof being effectivewhen the turbine and compressor are not operating, said means beingintended to prevent leakage of refrigerant from the compressor towardsthe turbine and to prevent exhaust leakage from the turbine towards thecompressor.

One embodiment of the invention will now be particularly described, byway of example with reference to the accompanying drawings, of which,

FIGURE 1 diagrammatically shows a refrigeration system applied in avehicle for the air conditioning of the vehicle, and,

FIGURE 2 is an enlarged cross-sectional elevation of a part of theturbine-compressor unit shown in FIG- URE 1.

Referring to FIGURE 1 of the drawings, the refrigeration system includesan evaporator 11 which is mounted in heat-exchange relation across aduct 12 which leads from the exterior of a vehicle to the interiorthereof. An electrically-driven fan 13 is provided ahead of theevaporator 11.

The refrigeration system also includes in conventional manner, acondensing unit generally indicated at 14 comprising a compressor 15, areceiver 16 and a condenser 17. The compressor 15 is of non-positivedisplacement, centrifugal type and its rotor 18 is mounted upon a shaft19. This shaft is arranged to be driven by a turbine 20, the rotor 21 ofwhich is also mounted upon the shaft.

The turbine casing is of torus shape and has an exhaust inlet 22 and anexhaust outlet 23. The inlet 22 is coupled to the exhaust manifold ofthe internal combustion engine (not shown) which powers the vehicle.

The inlet 24 of the centrifugal compressor 15 is connected by means of apipe 25 to the outlet side of the evaporator 11, a refrigerant inletservice valve 26 being provided in this pipe just upstream of the inlet24. A pipe 27 is branched from the pipe 25 at a point upstream of theservice valve 26 and is taken to the inlet side of vided in the pipe 27.

acts as a drier and a sight glass for the refrigerant. A pipe 33 istaken from the liquid receiver 16 through a thermostatically-operatedexpansion valve 34 to the inlet side of the evaporator 11. Thethermostat 34a associated with the valve 34 is positioned on the outletside of the evaporator 11 in the pipe 25.

Thus the evaporator, 11, compressor 15, receiver 16, condenser 17 andthe associated pipes constitute a closed circuit.

Static and dynamic refrigerant sealing means generally indicated at 35in FIGURE 1, are provided to the left of the compressor rotor 18 in thedrawing to prevent the escape of refrigerant from the system along theshaft 19 into the turbine 20 and also to prevent leakage of gas from theturbine into the compressor.

Referring now to FIGURE 2 of the drawings, the shaft 19 is mounted forrotation in a first bearing 36 and in a second bearing (not shown). Tothe left in the drawing of the compressor rotor 18 and surrounding theshaft 19 is a static sleeve 37. A helical pump 38 is formed upon theshaft 19 for lubricating a first bearing 36, lubricating oil being drawnin by' the pump from an inlet passage 39 through an annulus 40 formed inthe shaft. Drain oil passes from the bearing through a drain passage 41.In like manner a similar pump (not shown) is provided for lubrication ofthe second shaft bearing. To the right in the drawing of the annulus 40the shaft is formed with a double-helical grooving 42 to provide adynamic seal forming a portion of the means 35 and designed to take oilfrom the annulus 40 and to generate a pressure wedge at the position 43intermediate the effective length of the grooving and around itsperiphery to prevent leakage of refrigerant from the compressor towardsthe turbine when the shaft is rotating.

Associated with the static sleeve 37 is a two-part static sealingarrangement forming another portion of the means 35. The first part ofthis arrangement comprises a rubber sealing diaphragm 44 which issandwiched between casing components 45 and 46 and which is seated alsoupon a flanged portion 47 of the static sleeve 37. The second part ofthe static sealing arrangement comprises a rubber tubular member 48having a radially-inwardly directed and tapered head portion 49 which inthe static condition of the shaft 19 is an interference fit upon theexternal surface of thecylindrical portion of the static sleeve 37. Themember 48 is carried upon a sleeve 50 secured to the compressor rotor 18and thus when the rotor and shaft commence to rotate, the member 48 isalso rotated.

In operation of the vehicle 12, the exhaust-gas-powered turbine rotor 21drives the compressor rotor 18, heatladen refrigerant vapour being drawnin by the compressor from the evaporator 11 through the pipe 25 andrefrigerant inlet service valve 26. The compressor pumps this vapourthrough the outlet port 29 and the outlet service valve 31 into the pipe30, the high pressure vapour passing then into the condenser 17. Cooling air is driven over the outside of the tubes of the condenser 17 toabsorb the heat. The high pressure vapour then condenses and therefrigerant, now liquid under high pressure, passes into the receiver16, thereafter passing through the pipe 33 and the expansion valve 34into the evaporator 11, turing back into vapour,

in known manner, and taking heat from the air which is passing inheat-exchange relation with the evaporator 11 at it enters theinteriorof the vehicle through the duct 12. The cycle continues, thedifference in pressure on the two sides of the system keeping therefrigerant flowing to the evaporator 11 so that cooling of the airentering the interior of the vehicle is maintained.

The hot gas by-pass valve 28 is provided for control of the highpressure vapour permitted to pass into the condenser 17.

Suitable valve means (not shown) are incorporated in association withthe duct 12 which conveys the air to the interior of the vehicle.

During operation of the system thedynamic seal 42 is operative toprevent leakage of refrigerant towards the turbine and to preventleakage of exhaust gas from the turbine towards the compressor. Duringoperation, however, by virtue of the mass of the head portion 49 of thestatic sealing member 48, the centrifugal force arising with rotationcauses the head portion to be held deflected radially-outwardly awayfrom the external surface of the static sleeve 37 so that it has nocontact at all with this surface and thus is intended to suffer no wear.limits the extent of deflection of the member 48. When, however, theturbine-compressor unit is stationary and the dynamic seal isineffective, the static sealing member 48 is no longer held deflectedradially-outwardly and thus is in its interference sealing conditionwith respect to the external cylindrical surface of the static sleeve37. The two parts of the static sealing arrangement then prevent leakageof the refrigerant from the refrigeration system towards the turbine,but as soon as rotation of the shaft 19 recommences for restarting ofthe refrigera-' tion system, the interference fit of the member 48 uponthe static sleeve is quickly release.

The system is so arranged that a relatively large flow of refrigerant iscirculated at relatively low pressure, the temperature of therefrigerant passing into the evaporator 11 being only cold, for example,40 to 50 degrees Fahrenheit, rather than very cold as would be necessarywhere a. smaller mass flow of refrigerant was passing through theevaporator.

Dichlorodifluoromethane is preferable as refrigerant because it is ofsuch nature that the tip speed of the compressor rotor 18 is maintainedbelow sonic velocity .while pumping this refrigerant, and thus acritical 'gas speed from the compressor rotor is not reached in the'operating range required of this rotor when pumping the the compressoror an electric motor drive.

It has been found in the present embodiment that 4 from threeto fivehorse-power is required to drive the refrigeration system and by soarranging to obtain the refrigeration system driving power from theexhaust gases otherwise going to Waste into the atmosphere, this enablesa substantial proportion of this amount of horsepower to be utilised inthe traction of the vehicle.

Although in the embodiment above described, the compressor rotor is ofthe centrifugal type, this invention is in no way limited to such, ascompressors of other suitable type are used in other embodiments.Further, the invention is in no way limited to the singe stagecompressor and turbine arrangement, as in other An internally-taperedcylindrical member 51 embodiments, multi-stage compressor and/ orturbine units are employed.

Further, the invention is not limited to use in vehicles as in otherembodiments it is used in conjunction with stationary engine plant forcooling associated equipment or enclosures.

Again, in another embodiment of the invention, the turbine driving thecompressor of the refrigeration system is also arranged to drive anothercompressor, itself used for supercharging the engine.

Although in the embodiment described with reference to the drawings theturbine is driven by engine exhaust gases, in another embodiment theturbine is instead driven by the exhaust flow discharging from a steamturbine.

Further, although in the embodiment described with reference to thedrawings the compressor is of the nonpositive displacement type, inother embodiments the compressor is of the positive displacement type,either with or without a reduction gear in the drive to it from theturbine.

I claim as my invention:

1. A closed-circuit compressor-type refrigeration system including, incombination, a rotary compressor for circulating refrigerant within theenclosed circuit of the system, a turbine connectlble to an associatedengine in a manner whereby it is driven by the exhaust gases dischargingfrom that engine, a casing provided between said compressor and saidturbine, bearing means housed within said casing, a shaft mounted insaid bearing means and connecting'said turbine to said compressorthereby to drive the compressor when the turbine is operating, and sealmeans provided along said shaft including dynamic seal means effectiveonly when the system is operative, and static seal means effective onlywhen the system is inoperative, said dynamic and static seal means beingarranged in series.

, 2. A refrigeration system as claimed in claim 1 wherein saidcompressor is of the centrifugal type.

3. A refrigeration system as claimed in claim 1, wherein said dynamicseal means is of pressurized type and comprises: a fluid pump having anoutlet adjacent to said shaft; and a double-helical grooving cut in saidshaft and co-operable with said casing and in communication with saidfluid pump outlet.

4. A refrigeration system as claimed in claim 1, wherein said staticseal means includes: a stationary tubular member; a flexible tubularmember having a first end portion secured to said compressor and asecond end portion disposed about said stationary tubular member tothereby be rotatable with said compressor, said second end portion ofsaid flexible member being deformable radially-outwardly undercentrifugal force and having an inwardly-directed flange engageable influid sealing relation with said stationary tubular memher.

5. A refrigeration system as claimed in claim 4, wherein said flexibletubular member is of rubber-like material.

6. A refrigeration system as claimed in claim 5, wherein said fluid pumpis of helical form and includes helical grooving provided on said shaft,and wherein said pump outlet is in communication with said bearingmeans.

References Cited by the Examiner UNITED STATES PATENTS 2,608,423 8/ 1952Wilfley 277-134 2,670,613 3/ 1954 Haltenberger 62238 2,774,219 12/ 1956Kelley 62'243 2,781,209 2/ 1957 Jacobs 277-25 2,860,896 11/1958 Naumann277-134 2,898,745 8/ 1959 Weisel 62243 2,936,715 5/1960 Southam 277253,051,497 8/1962 Wigg 27'7134 3,076,656 2/1963 Hofmann 277-134 WILLIAM.J. WYE, Primary Examiner.

1. A CLOSED-CIRCUIT COMPRESSOR-TYPE REFRIGERATION SYSTEM INCLUDING, INCOMBINATION, A ROTARY COMPRESSOR FOR CIRCULATING REFRIGERANT WITHIN THEENCLOSED CIRCUIT OF THE SYSTEM, A TURBINE CONNECTIBLE TO AN ASSOCIATEDENGINE IN A MANNER WHEREBY IT IS DRIVEN BY THE EXHAUST GASES DISCHARGINGFROM THAT ENGINE, A CASING PROVIDED BETWEEN SAID COMPRESSOR AND SAIDTURBINE, BEARING MEANS HOUSED WITHIN SAID CASING, A SHAFT MOUNTED INSAID BEARING MEANS AND CONNECTING SAID TURBINE TO SAID COMPRESSORTHEREBY TO DRIVE THE COMPRESSOR WHEN THE TURBINE IS OPERATING, AND SEALMEANS PROVIDED ALONG SAID SHAFT INCLUDING DYNAMIC SEAL MEANS EFFECTIVEONLY WHEN THE SYSTEM IS OPERATIVE, AND STATIC SEAL MEANS EFFECTIVE ONLYWHEN THE SYSTEM IS INOPERATIVE, SAID DYNAMIC AND STATIC SEAL MEANS BEINGARRANGED IN SERIES.